LONG BEACH >> The recent death of a 16-year-old who hit his head on a San Diego Freeway overpass while standing up on the top level of a double-decker bus has raised concerns about the safety of the popular party transports.

Friends and fellow passengers of Mason Zisette, of Manhattan Beach, who was taken off life support on Saturday, said he was among a group that had been dancing on the top deck of the bus and that they had received no safety instructions prior to the ride.

The Long Beach-based Big Red Buses operates a fleet of three double-deckers similar to the one run by Starline Tours, on which Zisette was riding.

James Dulac, who recently bought Big Red Buses from longtime Long Beach businessmen Michael O’Toole and Peter Joseph, said the company has had a perfect safety record during its nine years of providing coastal tours on double-deckers.

Dulac credits the record, in part, to the use of a conductor, who monitors the passengers on the top level.

“We’re militant about putting a conductor up there,” he said.

Dulac said a conductor is always used on open-top buses and that there are restrictions on passengers standing on the top level.

The rules are strictly enforced, according to former owner O’Toole.

“We’ve actually let people off the bus,” he said, explaining that a person is expelled after repeated safety violations.

“The rules are important, as demonstrated by last weekend,” he said.

O’Toole said the rules are also verbally given to the passengers before their ride begins.

“We have been doing safety from day one,” he said. “It’s been very prominent from the beginning.”